Suction Anchor is an efficient mooring anchor that can carry heavy load in deep water. The uplifting bearing capacity of suction anchor is changed respect to loading position of anchor. There are previous researches on the behavior of suction anchor with different loading point and direction. In this study, holding capacity of suction anchor with large diameter according to loading positions was evaluated by p-y method which is widely used in the evaluation of lateral behavior of foundation based on the theory of beam on elastic foundation. Especially, size effect of suction anchor with large diameter, base shear and moment reaction are considered in this study. The analysis on holding capacity of suction anchor using p-y method is simple and can be easily used than other previous conventional analysis methods. Through comparing analysis results with established results of previous study, the holding capacity of suction anchors with the new proposed method using p-y method were estimated in this study.
Suction anchors, also called suction caisson or suction pile, are generally cylindrical steel units, open-end pipe pile and closed at the top. They are increasingly considered as an alternative foundation of offshore floating structure or wind turbines. Suction anchors were developed in the late 1970s and have seen most application for anchoring offshore floating structures to the seabed (Shin et al., 2017).
The predicting of laterally loaded suction anchors as the foundation is important in design. There are many methods which are estimating the holding capacity of the suction anchors under lateral loading. The conventional methods widely used are limit analyses, theories of elasticity and plasticity, finite-element, finite difference methods, and centrifuge test.
Researches on the holding capacity of the suction anchor have been conducted (Abyaneh et al., 2015, 2017; Aubeny and Murff, 2003; Bang and Cho, 1999; Bang and Cho, 2002; Choo et al., 2012; Randolph and House, 2002; Jeanjean et al., 2006, Zdravkovic et al., 2001). Broms (1964) proposed the treatment of laterally loaded piles that characterized lateral load capacity in terms of ultimate unit lateral resistance. Broms later then Matlock (1970) and Reese et al. (1975) proposed empirical estimates of Nps which is a dimensionless lateral unit resistance factor. It has been used significantly in engineering practice, however, also used for limited condition on soil and loading condition. Randolph and Houslby (1984) used plasticity theory predicting lateral load capacity of piles and anchors. The approach can be applied for only to lateral resistance at a point on a translating anchor sufficiently far from the ground surface. And the free surface cannot be considered in their study. Murff and Hamilton (1993) considered the effects of reduced resistance at the free surface and tip resistance at the bottom of the pile. The research involves a rotational mode of rigid body about a point on a caisson, pure translation and a plastic hinge in the pile. It also can apply for long and slender piles, however, not for short piles or suction anchor. Bang and Cho (1999) had conducted the geo-centrifuge test considering the development of three-dimensional normal and shear stresses along the circumference of the pile surface as well as a three dimensional soil failure wedge. The geo-centrifuge results were compared the analytical solution to validate the ultimate horizontal loading capacity of suction piles.
